The ability to alleviate clinically recognizable diseases, such as pellagra and pernicious anemia, by nutritional factors led to the discovery of several vitamins and to the association of definable disease states with specific nutrient deficiencies. Because these diseases are diagnosed clinically and can be confirmed by laboratory tests, nutritional treatment of these diseases was quickly incorporated into medical practice.
Although considerable evidence has accumulated for a broader link between nutrition and disease, behavior, performance and well-being of human-kind, the incorporation of such concepts into general medical practice has not been accomplished largely because methods for assessment of individual nutritional status are lacking. Data such as blood and urine levels of nutrients, degree of saturation of enzymes with coenzymes derived from specific vitamins, and analyses of hair have been compared with a range of normal values in attempts to determine nutrient deficiencies. However, such methods do not actually determine the nutritional requirements of an individual, and on the basis of biochemical individuality, nutritional requirements--particularly the quantitative needs--are known to vary significantly among different "normal" individuals. In short, these previous methods of assessment have merely determined the nutrient levels, nutrient intakes, etc. and compared these with the averages of control groups. These previously used methods did not allow for individual variations which affect everyone to a greater or lesser degree.
In the absence of suitable clinical tests for assessing individual status, attempts in medical practice to utilize nutritional therapy have been limited. A "well-balanced" diet sometimes with limited vitamin supplementation has been the most common approach in medical practice to nutrition of individual patients. More limited in medical practice has been the mega-vitamin approach, one which has received considerable criticism on the basis of limited experimental evidence for possible detrimental effects, lack of data concerning possible long term adverse effects, and lack of convincing evidence for a beneficial effect in the treatment of particular disease states.
For some time, it has been apparent that effective utilization of nutrition in medical practice is dependent upon the development of methods for assessing the nutritional status of each individual and identifying factors which limit the nutritional responses of each individual. It would be anticipated that optimizing nutrition for each individual would have a very significant impact on human health and productivity.
Several years ago I initiated an approach to this problem through an assessment of the nutritional variability of cell cultures derived from individuals participating in the study. After a number of potential types of cells had been considered, lymphocytes from blood were selected, primarily because of their availability on a routine basis from patients. Lymphocytes have the further advantage of being metabolically inactive until activated by a mitogen so that these cells carry information concerning past nutritional status and have little day to day variation in nutritional responses. In the activation and initiation of growth, the lymphocytes must carry out most of the reactions required of any of the growing cells of the body; consequently, it would be anticipated that abnormalities in the nutritional requirements or metabolism of lymphocytes would likely reflect the condition in other cells. Also, appropriate intervention by supplementation, or in the case of toxicities appropriate limitation of the toxic substance or reversal of its effect by dietary supplements, would be beneficial for the individual.
In order to develop such a method, it was necessary that lymphocytes be cultured in a chemically defined medium without the usual supplementation of fetal calf serum. Although activation of lymphocytes under serum-free conditions had been reported, difficulties reported in achieving the same results in different laboratories led to the suggestion that possibly trace serum contaminants or other artifacts were involved in the serum-free experiments. Serum albumin or unidentified serum macromolecules were reported to be absolutely essential for mitogen-induced DNA synthesis in human peripheral blood lymphocytes.
In initiating the present invention, a number of chemically defined media which had been used in cell culture were found to support only marginal activation and very limied growth of lymphocytes. It became apparent that new media would have to be developed in order to obtain significant growth responses. In order to obtain media suitable for assessment of the nutritional status of lymphocytes, it was necessary to develop a medium in which components were adjusted to minimal concentrations but at a level which would still not limit the optimal response of the lymphocytes. Each change required determination of the effect on the response of other components.